If the GMC finds him guilty, he could be struck off the medical register.

At 74, he admits he is too old to practise medicine, but says he is fighting the case to highlight his call for a change in the law.

Police caution

The former UN medical director openly admits travelling to the Isle of Man in October 2003 with around 60 Temazepam sleeping pills to assist fellow campaigner Patrick Kneen to end his life.

His blatant disregard for the law and his attitude to responsible prescribing is incompatible with his professional status

Alison Foster, for the GMC

Mr Kneen was too ill to take the medication and slipped into a coma, dying a few days later without Dr Irwin's assistance.

But Dr Irwin admitted planning to assist a suicide.

He was questioned by the Surrey Police over the incident last year because the prescription sleeping pills he was willing to supply are a class C drug.

He had obtained the medication via a prescription, originally in his own name, from the Moss Pharmacy in Cranleigh, the previous October.

A decision was taken not to proceed with the case but Dr Irwin received a caution in July 2004 - a move which resulted in the GMC hearing.

Alison Foster, for the GMC, told the panel the doctor "freely admitted" the charges against him.

"It's important to state this case is not about his right to hold his widely publicised views.

"This case is not about the morality or otherwise of assisted suicide.

"This case is about Dr Irwin's deliberate failure to conduct himself within the law."

'Twinning' arrangement

She told the hearing he had sought to "commit a serious criminal act", adding: "It is our case that his blatant disregard for the law and his attitude to responsible prescribing is incompatible with his professional status."

Dr Irwin admits several charges against him but denies that his actions were unprofessional, inappropriate and irresponsible.

He also denies they were likely to bring the medical profession into disrepute and that his actions amounted to serious professional misconduct.

Miss Foster said that, in a statement the doctor gave to police, "fails to recognise that this case is not about Dr Irwin's views but about his behaviour in breaking the law."

Dr Irwin, who says he has never actually helped anyone to die said before the hearing began: "Although our British society is in principle just, I strongly believe the existing law on assisted suicide is unjust and that, sometimes, a compassionate physician has a greater duty to a patient or a close friend rather than his or her duty to the state."

He added he would be asking the panel what their individual views on euthanasia are, to ensure he is given "a fair hearing".

And said he knew of several doctors, including himself, who had "twinning" arrangements with colleagues - each agreeing to help the other die should the need arise.

"If physicians are willing to help each other at the end of life, surely they are guilty of applying double standards if they do not extend this privilege to their terminally ill patients or close friends," he added.